The development and application of sensitive assays such as the enzyme-linked immunosorbent assay (ELISA) has made detection and measurement of salivary antibody relatively easy. The successful measurement of antibodies to specific antigens is directly dependent on the purity of the antigen preparation. The observation that whole saliva contain glycosyl- and fructosyl-transferase, dextranase and glucans complicates the measurement of antibody activity. Titers of antibody reactive with S. mutans whole cells and specific antigens are consistently higher in parotid than in whole saliva suggesting that a portion of the antibody is bound and unavailable for assay. Successful measurement of antibody in saliva may require use of ductal secretion or the separation of specific antibody from interacting and competing molecules.